Abstract: The invention provides compounds of formula (I) and pharmaceutically acceptable salts thereof, wherein A1 is —N? or —C(R3)=; A2 is —N? or —CH?; L is —NH—; B1 and B2 are independently —N? or —C(R2b)=; B3 and B4 are independently —C(R2b)=; no more than one R2b on B1, B2, B3 and B4 is other than hydrogen; R1a is hydrogen, halogen, C1-C3alkyl (n-alkyl) optionally substituted with one R4, or R1a is —NH2, —NH(C1-C3alkyl (n-alkyl)), —NH(C(?O)—C1-C2alkyl), —N(C1-C3alkyl (n-alkyl))2, —OC1-C3alkyl (n-alkyl), C1-C3haloalkyl (n-alkyl) or —OC1-C3haloalkyl (n-alkyl); R1b is hydrogen, halogen, C1-C3alkyl (n-alkyl), —OC1-C3alkyl (n-alkyl), —NH2, —NH(C1-C3alkyl (n-alkyl)) or —N(C1-C3alkyl (n-alkyl))2; R1a and R1b may together form a —CH?CH—CH?CH— moiety in which one or two non-adjacent CH are optionally replaced by N; R2a is halogen, C1-C6alkyl, C1-C6haloalkyl, cyclopropyl, cyclobutyl, —OR6, —NHC(?O)—C3-C6cycloalkyl, Cycle Q, —SF5 or group Y (formula (Y)); wherein X is a 3- or 4-membered carbocyclic ring and R8 is halogen, cy